Modern map displays, particularly those used in aircraft for flight planning and monitoring, are capable of displaying a considerable amount of information such as terrain information and flight planning information. The terrain information may include situational awareness terrain and cautions that identify potential hazards. Flight planning information may include, for example, flight path and altitude information useful to the pilot.
These electronic instrumentation displays continue to advance in sophistication, achieving increasingly higher levels of information density and, consequently, presenting a greater amount of visual information to be perceived and understood by the operator, e.g., the pilot. It is important that visual displays provide a proper cognitive mapping between what the operator is trying to achieve and the information available to accomplish the task.
It is important for pilots to know the position of the aircraft which they are operating (referred to herein as their “own-ship”) and the height of the surrounding terrain. Airport Moving Maps (AMM) are an overlay, for example, on a multi-function display/inertial navigation display (MFD/INAV), where terrain features like elevation are shown on the display. Depiction of the own-ship position reference point is extremely important.
Data driven charts (DDC) have a powerful ability to integrate chart information with aircraft position and flight management system (FMS) procedural routing. The minimum (or lowest) safe altitude is used in aviation to designate an altitude level deemed safe over a particular flight path or region. Generally, the minimum safe altitude is an altitude level that incorporates a safety buffer above the obstacles and/or terrain within a particular geographic region proximate to a route that an aircraft may travel. The minimum safe altitude is intended to ensure clearance over obstacles and terrain during flight.
Often, the minimum safe altitude is determined based on criteria provided by a governmental or regulatory organization. For example, in the United States, the Federal Aviation Administration defines criteria for the minimum safe altitude in the Federal Aviation Regulations. The regulations may provide a specific safety buffer for determining the minimum safe altitude, for example, an altitude of 1,000 feet above the highest obstacle within a horizontal distance of four nautical miles. By flying an aircraft at or above the minimum safe altitude, the pilot complies with the terrain and obstacle clearance requirements for the particular flight path.
However, there is a technical or functionality gap in current day avionics in providing timely procedure minimum altitude clearance information and alerting to the pilot. That is, when the flight management system (FMS) is programmed with a departure, arrival, en route jet airway, or instrument approach procedure there will be minimum altitudes that apply, for example, minimum en route altitude (MEA), minimum obstacle clearance altitude (MOCA), minimum crossing altitude (MCA), maximum authorized altitude (MAA), minimum holding altitude (MHA), minimum off route altitudes (MORA), and minimum reception altitude (MRA). MCA are displayed in the FMS legs page, but MOCA are not. MSA altitudes can be displayed within 25 nm of an aerodrome, but do not assist the pilot outside this 25 nm radius. The enhanced ground proximity warning system (EGPWS) is a ‘last ditch’ safe warning should the pilot descend below a safe altitude near terrain that typically requires an abrupt action on the part of the pilot.
This lack of obstruction clearance altitude awareness will be compounded in the future National Airspace System (NAS), when point-to-point RNAV (area navigation, or random navigation) routes will be the norm rather than the exception. This point-to-point clearance may be off route or without defined procedures. When the aircraft is flying in open airspace that is not defined by Victor or Jet Airways, or Instrument Procedures, there is not any display awareness for minimum obstruction clearance. Although many current aircraft are equipped with EGPWS, this is a terrain alerting system that warns of impending terrain closure and calls for aggressive maneuvering.
An airway can carry three or more altitude constraints: some for MRA, some for MCA, and some for MEA. See, for example, FIG. 1 illustrating the clutter 102 of information presented to the pilot upon executing a known procedure turn to an airport. To further complicate the situation, some segments require a step climb to be initiated when the next segment of the flight plan route is higher. Granted, most jets fly way above these altitudes and are just not concerned, in general. But lesser classes of aircraft, e.g., single or dual engine turboprops, and other general aviation complex piston aircraft, do not have the same level of performance and must be concerned.
A pilot may have the option to display a more clear presentation by removing clutter for the course he is to fly as shown in FIG. 2; however, this removes data that may be pertinent to the pilot's flight plan.
Accordingly, it is desirable to provide a system and method for displaying general terrain clearance awareness, whether the aircraft is off route, on airway, off procedure, or on procedure, so altitude thresholds, for example, off route obstruction clearance altitudes (OROCA) and minimum off route altitudes (MORA), are not violated and EGPWS alerts are avoided, while reducing clutter in displaying the information. Furthermore, other desirable features and characteristics of the exemplary embodiments will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.